US3955028A

US3955028A - Process for forming a flame retardant article and article thereof

Info

Publication number: US3955028A
Application number: US05/489,674
Authority: US
Inventors: Edward D. Weil
Original assignee: Stauffer Chemical Co
Current assignee: Stauffer Chemical Co
Priority date: 1974-06-10
Filing date: 1974-07-18
Publication date: 1976-05-04
Anticipated expiration: 1993-05-04

Abstract

Compounds of the formula:

Description

This is a continuation-in-part of U.S. Ser. No. 477,721, filed June 10, 1974, now abandoned.

TECHNICAL DESCRIPTION OF THE INVENTION

The present invention relates to tribromoneopentyl esters of phosphorus acids which exhibit reactive flame retardant properties. These compounds can be used as flame retardant additives, but have the particular feature of being flame retardant reactive components for textile finishing and, in some instances, as monomers which have flame retardant properties.

It is known that tribromoneopentyl alcohol can be made into certain phosphorus esters which have flame retardant additive characteristics. These esters can be used as flame retardant additives to confer flame retardancy on a variety of materials. Phosphates and alkyl- or arylphosphonates are, for example, described in U.S. Pat. No. 3,824,205 to Carpenter et al. Bis(tribromoneopentyl) tribromoneopentyl phosphonate is described in U.S. Pat. No. 3,456,041 to Burk et al. The compounds described in these two patents, however, differ significantly from the compounds of this invention since the former compounds lack structural members which will react with the textiles or polymers that one may desire to flame retard. The halogen atoms contained in those compounds of the prior art are all of the relatively unreactive neopentyl type, and their relative inertness limits their use to being merely additives rather than reactive flame retardant monomers.

The compounds of the present invention retain the advantage of these prior art compounds with respect to having their bromine content in the heat-stable and light stable tribromoneopentyl form. However, the compounds of the present invention, unlike the above-described prior art compounds, contain reactive structural units and therefore have a broader field of utility as reactive flame retardants. The compounds of this invention have the following structure:

[(BrCH.sub.2).sub.3 CCH.sub.2 O].sub.2 P(O)R

where R can be --CH=CH₂, --CH₂ X, --OR'OC(O)CH=CH₂, --OROC(O)C(CH₃)=CH₂, --O(R'O)_n H, --OH, --Cl, and --NR"R'", where R' is a lower alkylene or haloalkylene group, e.g., a C₁ -C₄ group, R" and R'" are the same or different and are selected from the group consisting of hydrogen, lower alkyl, e.g., C₁ -C₈, preferably C₁ -C₄, phenyl, hydroxy-lower-alkyl, e.g., hydroxyl C₁ hydroxy C₈ or, preferably C₁ -C₄ alkyl, and allyl groups, where X is a halogen, e.g., chlorine or bromine, and where n is an integer between 1 and 20. Preferred compounds are bis(tribromoneopentyl) vinylphosphonate, bis(tribromoneopentyl) chloromethylphosphonate, bis(tribromoneopentyl) acryloxyethyl phosphate, bis(tribromoneopentyl) acryloxypropyl phosphate, bis (tribromoneopentyl) methacryloxyethyl phosphate, bis(tribromoneopentyl) methacryloxypropyl phsophate, bis(tribromoneopentyl) acryloxychloropropyl phosphate, bis(tribromoneopentyl) methacryloxychloropropyl phosphate, bis(tribromoneopentyl) phosphorochloridate and bis(tribromoneopentyl) acid phsophate and its salts.

The compounds of this invention have reactive functional groups for R which are well adapted to serve as means for attaching the compounds to textiles. When R is vinyl or terminates in an acrylate or methacrylate group the compounds are polymerizable by free radical mechanisms and can be polymerized or copolymerized in situ on textiles by means of graft polymerization as described in U.S. Pat. No. 3,695,925 to Weil. These monomers can also be polymerized or copolymerized to form useful flame retardant emulsions, films, coatings and molding resins. When R is CH₂ X, where X is a halogen, e.g., preferably chlorine or bromine, although permissably fluorine or iodine, the compound is sufficiently reactive as an alkylating reagent to allow for attachment via an ether linkage to cellulose that has been treated with alkali in a manner similar to that described by Drake et al. in Textile Research Journal, Vol. 29; 270,884 (1959). When R is --NR"R'" the compounds can phosphorylate cellulose in a manner described for phosphoramides by Morris et al. in Textile Research Journal, Vol. 43: 336 (1973), or when either R" or R'", or both, are hydrogen or hydroxyalkyl, they can be bonded to textiles in the manner described in U.S. Pat. Nos. 2,838,228 to Glade et al., 3,767,736 to Burke, and 3,746,572 to Weil et al.

The vinyl and acrylic monomers of the invention can also be used to make flame retardent polymers and copolymers for films, sheets, molded objects, and coatings. The alcohol-group containing reactive compounds of the invention can furthermore be incorporated into flame retardant polyesters and polyurethanes by condensation polymerizations.

The phosphorochloridate, i.e., when R is --Cl, can be used per se as a reactive flame retardant in the phosphorylation process described by Kiselev and Danilov, Russian Pat. No. 159,524 or by Schwenker and Pascu, Textile Research Journal, Vol. 27, pp. 173 and following (1957), or can be converted to other useful products. It can, for example, be reacted with an epoxide, e.g., ethylene oxide, propylene oxide, epichlorohydrin, glycidyl acrylate, glycidyl methacrylate, optionally, in the presence of a suitable Lewis acid catalyst, such as TiCl₄, AlCl₃, etc., to obtain a phosphate having a primary chloroalkyl group. The phosphorochloridate group can alternatively be reacted with an amine, HNR"R'", to obtain the phosphoramidates of the invention where R is NR"R'". The phosphorochloridate can also be reacted with diols or polyols to make a hydroxyalkyl bis (tribromoneopentyl) phosphate which can be used as a reactive cellulose flame retardant by using the process described in U.S. Pat. No. 3,746,572 to Weil.

Compounds falling within the scope of the formula described above can be formed by reaction in the liquid phase, optionally in the presence of a non-polar organic solvent, e.g. benzene, toluene, xylene, a C₅ -C₁₂ hydrocarbon, e.g., hexane, heptane, etc., of two molar equivalents of tribromoneopentyl alcohol with Cl₂ P(O)R, where R is as defined above, by heating, e.g., between about 30°C. -100°C., until two molar equivalents of hydrochloric acid are given off, or, alternatively, with the addition of at least two moles of a suitable base, e.g., triethylamine, to abstract the two molar equivalents of hydrochloric acid. Heating can be used in the latter process embodiment to accelerate the process.

An alternative process for use in making bis (tribromoneopentyl) phosphorochloridate is the reaction of two molar equivalents of tribromoneopentyl alcohol with POCl₃, optionally in a non-polar organic solvent, with heating to drive off two molar equivalents of hydrochloric acid.

The compounds of the present invention have in general an advantage as flame retardant textile finishing compounds over related dibromopropyl esters known to the prior art. The present compounds show much greater resistance to heat, to light and to strong bases, e.g., harshly alkaline non-phosphate detergents. This latter advantage is of importance when the compounds are to be used in clothing, carpeting, draperies, furniture upholstery and the like. The vinyl containing monomeric compounds can also be copolymerized with other vinyl compounds, e.g., the vinyl halides, vinyl acetate and the vinylidene halides, into polymers which yield coatings, films, and molded articles possessing good light stability.

The following Examples illustrate the present invention:

EXAMPLE 1

A mixture of 129.5g tribromoneopentyl alcohol, 35g of vinylphosphonyl chloride, 78 ml. of triethylamine, and 300 ml. of methylene chloride was refluxed for one day then evaporated to dryness. The residue was redissolved in methylene chloride, was washed with water and sodium bicarbonate solution, and then was dried over magnesium sulfate, was filtered and was evaporated to 100°C. at 0.1 mm. The product was a viscous syrup which crystallized upon standing. The nuclear magnetic resonance (n.m.r.) spectrum showed a ratio of about 5.3 aliphatic protons/vinyl proton (theory -- 16:3, or 5.33:1 for the indicated product).

After recrystallization from slightly aqueous ethanol, the product, bis(tribromoneopentyl) vinylphosphonate, was a crystalline solid having a melting point of 71°-72°C. Anal.: Calcd. for C₁₂ H₁₉ O₃ Br P: %Br 66.5, %P 4.3; Found: %Br 67.0, %P 4.3.

EXAMPLE 2

A mixture of 33.5g vinyl chloride, 16.5g of the bis (tribromoneopentyl) vinylphosphonate, 15 ml of water, 15 ml of 1% polyvinyl alcohol solution, and 1.5 ml g 5% isopropyl peroxydicarbonate in heptane was charged to a polymerization vessel, and the mixture was agitated for 16 hours at 45°C. The suspension copolymer of vinyl chloride and bis(tribromoneopentyl) vinylphosphonate thus obtained was dried. A quantitative yield of polymer was obtained and an infrared spectrum on the material did not show any residual unsaturation from the phosphonate.

Comparison was made with representatives of prior art types of flame retarded acrylonitrile -- butadiene -- styrene (ABS) resins, those containing Sb₂ O₃ and various chlorinated organic compounds and the ABS-polyvinyl chloride-Sb₂ O₃ polyblends. The former tend to have reduced deformation temperatures under load. Several formulations containing the copolymer formed earlier in this Example were milled to obtain comparison data with flame retardant ABS. The results are summarized in the Table.

              TABLE                                                       
______________________________________                                    
Sample                                                                    
      Blend Composition (*)                                               
                        L.O.I.(***)                                       
                                  Physical                                
No.                               Appearance                              
______________________________________                                    
1     ABS** (Control)   17.49     Tough Sheet                             
2     ABS** + 22 phr. (parts per                                          
                        23.49     Brittle                                 
      hundred) Dechlorane****                                             
3     ABS** + 21 phr.   21.39     Tough                                   
      copolymer from Example 2                                            
      and 2.3 phr. Sb.sub.2 O.sub.3                                       
4     ABS** + 21 phr.   24.14     Tough                                   
      copolymer from Example 2                                            
      and 8 phr Sb.sub.2 O.sub.3                                          
5     60% ABS** + 40%   24.64     Tough                                   
      copolymer from Example 2                                            
______________________________________                                    
 *All the materials milled well and had sufficient heat stability. All    
 parts per hundred (phr) are based on the ABS resin as 100.               
 **Acrylonitrile-butadiene-styrene (Lustran 420 - Monsanto)               
 ***Limiting Oxygen Index: The test procedure (ASTM D-2863) is described i
 Fenimore et al., Modern plastics, November, 1966. A higher LOI indicates 
 better flame retardancy.                                                 
 ****The Diels-Alder diadduct of hexachlorocyclopentadiene and            
 cylooctadiene -1,5 (Hooker Chemical Corp.)

The bromine containing copolymer of the present invention produced flame retardancy in ABS which compared favorably with the types of flame retardant ABS resins known to the prior art. The copolymer additive did not detract from the impact strength of the ABS whereas the Dechlorane produced a brittle sheet.

EXAMPLE 3

To a stirred solution of 64.8g tribromoneopentyl alcohol and 18.5g chloromethylphosphonic dichloride in 200 cc of benzene was added 34 ml of triethylamine. After the exotherm had subsided, the mixture was refluxed for 2 hours on the steam bath, was cooled, and 1 liter of water was added. The organic layer was separated and was dried over magnesium sulfate, was filtered, and was diluted with heptane. The diluted filtrate was then partly evaporated until crystals began to form, was then refrigerated overnight, and the crystalline product was then filtered off. The product, i.e., bis(tribromoneopentyl) chloromethylphosphonate, was colorless and had a melting point of 118°C. The infrared spectrum showed no OH band, but a phosphonate P=O multiplet centered at 1252 cm.sup.^-1. When applied at 15% add-on to alkali treated cellulose and heated at 150°C. for 1 hour, a wash-durable flame retardant finish is produced.

EXAMPLE 4

To a solution of 130 g (0.4 mole) tribromoneopentyl alcohol and 29.6g (0.2 mole) dimethylphosphoramidic dichloride in 200 ml. benzene was added 60 ml triethylamine. The mixture was refluxed for a period of 11/2 days on a steam bath, was cooled, filtered, and the filtrate was evaporated. The residue was redissolved in chloroform, was washed with water, filtered with charcoal, diatomaceous earth and magnesium sulfate, and the filtrate then stripped at 100°C. and 0.1 mm. The product (138.4g) was a very viscous syrup, whose n.m.r. spectrum showed the P--NCH₃ protons at δ 2.75 ppm, the P--O--CH₂ --protons at δ 4.1 ppm and the --CH₂ Br protons at δ 3.6 ppm relative to tetramethylsilane as the standard reference compound. The integrals for the three types of protons supported that the structure was [(BrCH₂)₃ CCH₂ O]₂ P(O)N(CH₃)₂, i.e., bis(tribromoneopentyl)N,N-dimethylphosphoramidate. In like manner, diallylphosphoramidic dichloride is reacted with tribromoneopentyl alcohol to obtain [(BrCH₂)₃ CCH₂)]₂ P(O)N(CH₂ CH=CH₂)₂, the corresponding N,N-diallyphosphoramidate, as a viscous syrup. Impregnation of cotton cloth by 20% by weight of either of the above products affords a flame retardant finish. Fixation of the N,N-dimethyl amide is achieved by warming the cloth at 160°C. for 10 minutes. The N,N-diallylamide is rendered wash durable by exposure of the impregnated cloth to 2-4 megarads of electron beam radiation.

EXAMPLE 5

A mixture of 648g (2 moles) of tribromoneopentyl alcohol and 153g (1 mole) of phosphorus oxychloride in 1000 ml of perchloroethylene is refluxed for about 3 hours until hydrogen chloride evolution dwindles to a negligible rate. The solution was cooked and filtered to remove a small by-product amount of tris(tribromoneopentyl) phosphate. The filtrate was then partially evaporated and cooled further to induce crystallization of the major product, bis(tribromoneopentyl) phosphorochloridate, as a colorless crystalline solid, m.p. 98°-99°. Analysis: Calcd. for C₁₀ H₁₆ Br₆ ClO₃ P: %Cl 4.9; Found: %Cl 4.9.

Preparation of Ester Derivatives Method A

To the chloride plus the indicated alcohol in equimolar amounts, dissolved in benzene, along with 50 ppm of t-butylhydroquinone is added 10% over the equimolar amount of triethylamine. After the spontaneous exotherm subsides, the mixture is heated to reflux for 3 hours, then cooled, filtered free of triethylamine hydrochloride, washed with dilute hydrochloric acid, dilute sodium carbonate solution, dried over MgSO₄, filtered with charcoal. The filtrate is evaporated to 100°C. under aspirator vacuum to remove solvent.

Method B

The chloride and the indicated glycidyl ester are mixed in equimolar amounts, 0.3% by weight titanium chloride is added as catalyst and the mixture is warmed on a steam bath and is held until infrared bands at 3.3 and 8 microns characteristic of the epoxy group have substantially disappeared. The product is then dissolved in chloroform, washed with dilute sodium carbonate solution, dried over MgSO₄, filtered with charcoal, and the filtrate evaporated to 100°C. under aspirator vacuum.

                                  TABLE                                   
__________________________________________________________________________
COREACTANT USED METHOD       PRODUCT             DESCRIPTION              
__________________________________________________________________________
CH.sub.2 = CHCOOCH.sub.2 CH.sub.2 OH                                      
                A     CH.sub.2 =CHCOOCH.sub.2 CH.sub.2 OP(O)[OCH.sub.2    
                      C(CH.sub.2 Br).sub.3 ].sub.2                        
                                                 Nearly colorless,        
                                                 waxy solid               
CH.sub.2 =C(CH.sub.3)COOCH.sub.2 CH.sub.2 OH                              
                A     CH.sub.2 =C(CH.sub.3)COOCH.sub.2 CH.sub.2 --OP(O)[OC
                      H.sub.2 C(CH.sub.2 Br).sub.3 ].sub.2                
                                                 Nearly colorless         
                                                 waxy solid               
CH.sub.2 =CHOOC.sub.2 H.sub.3 (CH.sub.3)OH)                               
                A     CH.sub.2 =CHCOOC.sub.2 H.sub.3 (CH.sub.3)--OP(O)[OCH
                      .sub.2 C(CH.sub.2 Br).sub.3 ].sub.2                 
                                                 Nearly colorless oil     
CH.sub.2 =(CH.sub.3)COOC.sub.2 H.sub.3 (CH.sub.3)(OH)                     
                A     CH.sub.2 =C(CH.sub.3)COOC.sub.2 H.sub.3 (CH.sub.3)--
                      OP(O)[OCH.sub.2 C(CH.sub.2 Br).sub.3 ].sub.2        
                                                 Nearly colorless oil     
HOCH.sub.2 CH.sub.2 OH                                                    
                A     HOCH.sub.2 CH.sub.2 OP(O)[OCH.sub.2 C(CH.sub.2      
                      Br).sub.3 ].sub.2          Colorless waxy solid     
                      and C.sub.2 H.sub.4 OP(O)[OCH.sub.2 C(CH.sub.2      
                      Br).sub.3 ] .sub.2                                  
HOCH.sub.2 CH.sub.2 OCH.sub.2 CH.sub.2 OH                                 
                A     HOCH.sub.2 CH.sub.2 OCH.sub.2 CH.sub.2 OP(O)[OCH.sub
                      .2 C(CH.sub.2 Br).sub.3 ].sub.2 and                 
                                                 Colorless syrup          
                      C.sub.4 H.sub.8 O.sub.3 [P(O)[OCH.sub.2 C(CH.sub.2  
                      Br).sub.3 ].sub.2 ].sub.2                           
∠                                                                   
CH.sub.2 =CHCOOCH.sub.2 CH--CH.sub.2                                      
                B     CH.sub.2 =CHCOOC.sub.3 H.sub.5 Cl--OP(O)[OCH.sub.2  
                      C(CH.sub.2 Br).sub.3 ].sub.2 *                      
                                                 Colorless syrup          
O                                                                         
∠                                                                   
CH.sub.2 =C(CH.sub.3)COOCH.sub.2 CH--CH.sub.2                             
                B     CH.sub.2 =C(CH.sub.3)COOC.sub.3 H.sub.5 Cl--OP(O)[OC
                      H.sub.2 C(CH.sub.2 Br).sub.3 ].sub.2 *              
                                                 Colorless                
__________________________________________________________________________
                                                 syrup                    
 *The C.sub.3 H.sub.5 Cl group is believed to be a mixture of --CH(CH.sub.
 Cl)CH.sub.2 -- and --CH.sub.2 CH(CH.sub.2 Cl)-- isomers

EXAMPLE 6

To a solution of 36.5g (0.05 mole) of bis(tribromoneopentyl) phosphorochloridate, made as described in Example 5, in 100 cc. of tetrahydrofuran was added 20g. (0.2 mole) of diethanolamine with stirring. The mixture was stirred for 4 hours, then diluted with 100cc. of water causing deposition of an oil. The tetrahydrofuran was removed under aspirator vacuum and the residual crude product was a solid, m.p. 121°-130°C. The product after recrystallization from methanol-water mixture was a colorless crystalline solid, m.p. 138°-139°C., and was found to have an n.m.r. spectrum consistent with bis (tribromoneopentyl) N,N-bis(2-hydroxyethyl)phosphoramidate. Analysis: Calcd. for C₁₄ H₂₆ O₅ PNBr₆ : %N 1.76 Found: %N 1.60. The product when applied (in methanolic solution) to cotton-polyester at 15% dry add-on, along with dimethyloldihydroxethyleneurea at 10% dry add-on and cured in the manner of Example 1 of Weil U.S. Pat. No. 3,746,572 imparts as wash-durable flame retardant finish.

In like manner to the above preparative reaction, bis tribromoneopentyl) phosphorochloridate in various solvents is reacted with various amines as shown in the Table:

                                  TABLE                                   
__________________________________________________________________________
AMINE     SOLVENT    PRODUCT         DESCRIPTION                          
__________________________________________________________________________
Aniline   Benzene C.sub.6 H.sub.5 NHP(O)[OCH.sub.2 C(CH.sub.2 Br).sub.3   
                  ].sub.2            Colorless crystalline solid, -   mp  
                                     95.5-96.5°. Analysis: Calcd.  
                                     -   for C.sub.16 H.sub.22 O.sub.3    
                                     PNBr.sub.6 : N 1.76. -   Found: N    
                                     1.60.                                
Ammonia   Benzene NH.sub.2 P(O)[OCH.sub.2 C(CH.sub.2 Br).sub.3 ].sub.2    
                                     Colorless crystalline solid, -   mp  
                                     103-104.5°C. Anal: Calcd.     
                                     for C.sub.10 H.sub.18 O.sub.3        
                                     PNBr.sub.6 : N 1.97.                 
                                     Found: N 1.98                        
Methylamine                                                               
          Benzene CH.sub.3 NHP(O)[OCH.sub.2 C(CH.sub.2 Br).sub.3 ].sub.2  
                                     Colorless crystalline solid          
Monoethanolamine                                                          
          Tetrahydrofuran                                                 
                  HOCH.sub.2 CH.sub.2 NHP(O)[OCH.sub.2 C(CH.sub.2         
                  Br).sub.3 ].sub.2  Colorless Wax                        
__________________________________________________________________________

The phosphoramidates given in the Table having an NH group are converted to the corresponding --N(CH₂ OH)-- compound by heating at 80°-100°C. for 4 hours with an equimolar amount of formaldehyde (as paraformaldehyde) plus 3% triethylamine as catalyst.

EXAMPLE 7

A solution of bis(tribromoneopentyl) phosphorochloridate in benzene was stirred with water. Crystalline solids slowly came out, and were removed by filtration. The product was a colorless crystalline solid, m.p. 130°C. Titration with standard 0.1-N NaOH in aqueous acetone medium or KOH in methanol showed it to have an equivalent weight of 710 corresponding to [(CHBr)₃ CCH₂ O]₂ P(O)(OH), bis(tribromoneopentyl) hydrogen phosphate. The aqueous acetone sodium salt solution or the alcoholic potassium salt solution was applied to cotton polyester fabric to obtain a dry add-on of 20% of the alkali metal salt of bis(tribromoneopentyl) acid phosphate. Fixation of the finish was achieved by applying a solution of magnesium chloride, which gives in situ formation of the water-insoluble magnesium salt of bis(tribromoneopentyl) hydrogen phosphate. The resultant finish imparts flame retardant properties and is wash-durable.

One or more of the compounds formed herein can be used to flame retard a wide variety of normally flammable substrates by being incorporated either in or on said substrates as either an additive or as a reactant with said substrate in an amount which is effective to flame ratard the substrate. Examples are fibrous materials, which for purposes of this invention include cotton, wool, silk, linen, rayons, cellulose acetate, acrylic, polyester, nylon, polyolefin, including polypropylene, blends such as cotton-polyester, and other organic fibers, yarns, and fabrics.

The polymers which can be flame retarded by the compounds of this invention include urea -- aldehyde resins, melamine -- aldehyde resins, urea -- melamine-aldehyde resins, phenol-- aldehyde resins, alkyd resins, the various vinyl type polymeric materials (both homopolymers and copolymers) including those comprising homo- and copolymers of acrylonitrile, styrene, vinyl acetate, the vinyl and vinylidene halides, butadiene, isoprene and so forth. The compounds can be incorporated in the above polymer materials during their formulation or can be used as a coating on the finished article. The amount of compound that must be incorporated either in or on the normally flammable substrate will vary between about 1 wt % and 40 wt % of the substrate depending upon the particular type of substrate chosen.

Claims

What is claimed:

1. A process for flame retarding a normally flammable substrate, which comprises treating said substrate with an effective amount of at least one compound of the formula

[(BrCH.sub.2).sub.3 CCH.sub.2 O].sub.2 P(O)R

wherein R is selected from the group consisting of --CH=CH₂, --CH₂ X, --OR'OC(O)CH=CH₂, and --NR"R'", where R' is a C₁ -C₄ alkylene group, R" and R'" are the same or different and are selected from the group consisting of hydrogen, lower alkyl, phenyl, hydroxy lower alkyl and allyl, and X is selected from the group consisting of chlorine and bromine, to thereby incorporate said compound in or on said substrate.

2. A process as claimed in claim 1 wherein the compound is bis(tribromoneopentyl) vinylphosphonate.

3. A process as claimed in claim 1 wherein the compound is bis(tribromoneopentyl) chloromethylphosphonate.

4. A process as claimed in claim 1 wherein the compound is bis(tribromoneopentyl) acryloxyethyl phosphate.

5. A process as claimed in claim 1 wherein the compound is bis(tribromoneopentyl) acryloxypropyl phosphate.

6. A process as claimed in claim 1 wherein the compound is bis(tribromoneopentyl) acryloxychloropropyl phosphate.

7. A flame retardant article formed by the process of claim 1.

8. An article as claimed in claim 7 wherein the normally flammable substrate is a fibrous material.

9. An article as claimed in claim 7 wherein the normally flammable substrate is an organic polymeric material.

10. An article as claimed in claim 7 wherein the amount of compound incorporated therein ranges from about 1% to 40% by weight of the substrate.